In an electrophotographic image forming method, examples of surface properties required for belt members such as a fixing belt and an intermediate transfer belt include: low surface energy necessary for preventing extraneous materials from adhering to the surfaces of the belt members during separation of an image supporting medium supporting a toner image or a fixed image obtained, by fixing the toner image; wear resistance under frictional stress and separation stress; and long service life (see, for example. Patent Literatures 1 and 2).